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Astron. Astrophys. 319, 52-66 (1997)


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AGNs with composite spectra *

P. Véron 1, A.C. Gonçalves 1, 2 and M.-P. Véron-Cetty 1

1 Observatoire de Haute-Provence (CNRS), F-04870 Saint Michel l'Observatoire, France
2 Centro de Astrofísica da Universidade do Porto, Rua do Campo Alegre 823, 4150 Porto, Portugal

Received 11 April 1996 / Accepted 22 July 1996

Abstract

The use of the Baldwin et al. (1981) or Veilleux & Osterbrock (1987) diagnostic diagrams allows the unambiguous classification of the nuclear emission line regions of most galaxies into one of three categories: nuclear HII regions or starbursts, Seyfert 2 galaxies and Liners. However, a small fraction of them have a "transition" spectrum.

We present spectral observations of 15 "transition" objects at high-dispersion (66Å mm-1) around the H [FORMULA], [FORMULA] and/or H [FORMULA], [FORMULA] emission lines. We show that most of these spectra are composite, due to the simultaneous presence on the slit of a Seyfert nucleus and a HII region.

Seyfert 2s and Liners seem to occupy relatively small and distinct volumes in the three-dimensional space [FORMULA], [FORMULA], [FORMULA].

Key words: galaxies: nuclei – galaxies: active – galaxies: Seyfert

* Based on observations made at the Observatoire de Haute-Provence (CNRS), France

Send offprint requests to: P. Véron

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998

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